Successful disinfection of trumpet mouthpieces using domestic steam disinfection

There have been numerous reports in the literature describing the diversity of microbial flora isolated from woodwind and brass instruments, with potential infection risks for players, especially when such instruments are shared. Steam disinfection has become established as a trusted method of decontamination; however, there have been no reports on the employment of this technology to disinfect parts of musical instruments, hence it was the aim of this study to examine the fate of bacterial and yeast pathogens on artificially contaminated trumpet mouthpieces and to evaluate whether such disinfection is an effective method of disinfection for such instrument parts. Trumpet mouthpieces were artificially contaminated with 18 microbial strains (17 bacteria from four genera (Enterococcus, Escherichia, Staphylococcus and Streptococcus) and one yeast (Candida)), each at an inoculum density of approximately 1·5 × 10⁷ colony forming units and subjected to a disinfection cycle. The experiment was repeated including 50% (v/v) sterile sputum as soil. No bacteria or yeast organisms were recovered post disinfection, including following recovery and with nonselective cultural enrichment techniques.     

Deliberately infecting healthy volunteers with malaria parasites: Perceptions and experiences of participants and other stakeholders in a Kenyan-based malaria infection study

Controlled human malaria infection (CHMI) studies involve the deliberate infection of healthy volunteers with malaria parasites under controlled conditions to study immune responses and/or test drug or vaccine efficacy. An empirical ethics study was embedded in a CHMI study at a Kenyan research programme to explore stakeholders’ perceptions and experiences of deliberate infection and moral implications of these. Data for this qualitative study were collected through focus group discussions, in-depth interviews and non-participant observation. Sixty-nine participants were involved, including CHMI study volunteers, community representatives and research staff. Data were managed using QSR Nvivo 10 and analysed using an inductive-deductive approach, guided by ethics literature. CHMI volunteers had reasonable understanding of the study procedures. Decisions to join were influenced by study incentives, trust in the research institution, their assessment of associated burdens and motivation to support malaria vaccine development. However, deliberate malaria infection was a highly unusual research strategy for volunteers, community representatives and some study staff. Volunteers’ experiences of physical, emotional and social burdens or harms were often greater than anticipated initially, and fluctuated over time, related to specific procedures and events. Although unlikely to deter volunteers' participation in similar studies in furture, we argue that the dissonance between level of understanding of the burdens involved and actual experiences are morally relevant in relation to community engagement, informed consent processes, and ongoing support for volunteers and research staff. We further argue that ethics oversight of CHMI studies should take account of these issues in deciding whether consent, engagement and the balance of benefits and harms are reasonable in a given context.     

A recombinant foot-and-mouth disease virus antigen inhibits DNA replication and triggers the SOS response in Escherichia coli

Abstract The 3D gene of foot-and-mouth disease virus encodes the viral RNA dependent RNA polymerase, also called virus infection associated (VIA) antigen, which is the most important serological marker of virus infection. This 3D gene from a serotype Cl virus has been cloned and overexpressed in Escherichia coli under the control of the strong lambda lytic promoters. The resulting 51 kDa recombinant protein has been shown to be immunoreactive with sera from infected animals. After induction of gene expression, an immediate and dramatic arrest of cell DNA synthesis occurs, similar to that produced by genotoxic doses of the drug mitomycin C. This effect does not occur during the production of either a truncated VIA antigen or other related and non-related viral proteins. The inhibition of DNA replication results in a subsequent induction of the host SOS DNA-repair response and in an increase of the mutation frequency in the surviving cells.     

Distribution and multiplication of Ralstonia solanacearum strain race 1 biovar 4 in vegetable sweet potato cuttings

Ralstonia solanacearum (RS) race 1 biovar 4 (R1bv4), causal agent of bacterial wilt in vegetable sweet potato (VSP), is often latent in VSP vines and is important in introduction of the pathogen to newly planted fields. In this study, the effects of biological and environmental factors on the distribution and multiplication of R1bv4 in VSP tissues were examined. Based on stem-injection inoculation, the R1bv4strain of NC01 could cause 49.0% and 33.0% wilting on VSP cultivars TN71 and WS, respectively. The populations of NC01 in diseased TN71 and WS were 10⁸–10⁹ cfu/g tissue at 28th day after inoculation. On the other hand, the R1bv4 could not cause symptom in cultivars of TN57 and VSPSL-1 vine and the NC01 was confined to near the injection sites. Temperature tests indicated that NC01 could cause 28.0% and 14.0% wilting on cultivar TN71 at 28 and 20°C, respectively. Moreover, the populations of NC01in diseased plants were 1.6 × 10⁹ and 7.9 × 10⁸ cfu/g tissue at 28 and 20°C, respectively. The distribution of NC01 in VSP stem indicated that the isolation frequency of NC01 was lower than 31.0% in terminal shoots or erect stems and 45.0 to 100.0% in creeping stem after 8 wks planted in infested soil (10⁶ cfu/g soil). The results demonstrated that terminal shoots or erect stems were not common carrier for transmitting R1bv4. Furthermore, two R1bv4 strains, NC01 and HsinT01, were examined the ability for latent infection on cv. TN71. The results revealed that NC01 and HsinT01 showed different ability of latent infection on cultivar TN71. NC01 had lower percentage (46.8% and 45.1%) than HsinT01 (93.4% and 75.3%) at 20 and 28°C.     

Alginate embedding and subsequent sporulation of in vitro-produced Conidiobolus thromboides hyphae using a pressurised air-extrusion method

Conidiobolus thromboides is an entomophthoralean fungus with potential as a biological control agent of aphids. However, its application in biological control is limited due to its formulation requirements. The objective of this study was to develop and optimise a novel air-extrusion method to embed C. thromboides hyphae at high density in alginate pellets. An orthogonal experimental design was used to investigate selected combinations of parameters known to affect hyphal density within pellets. The diameter of pellets produced, and the calculated density of hyphae within them, ranged from 0.18 ± 0.09 to 3.17 ± 0.06 mm and from 0.02 to 350.56 mg/mm³ respectively. These data were used to predict the optimal parameter combination to deliver the greatest density of hyphae of C. thromboides per pellet: 1% sodium alginate, a 1:2 ratio of hyphae to sodium alginate, an orifice diameter of 0.232 mm and an air pressure of 0.05 MPa. Pellets made under the optimal conditions predicted produced a mean total of 4.3 ± 0.6 × 10⁵ conidia per pellet at 100% relative humidity which was significantly greater than the mean total number of conidia produced from infected aphid cadavers of comparable size (9.35 ± 0.85 × 10⁴) (p < 0.001). In conclusion, air-extrusion embedding appears to be a promising method for formulating in vitro-produced hyphae of C. thromboides for use in biological control.     

Phylogeography of the parasitic fly Batrachomyia in the Wet Tropics of north-east Australia, and susceptibility of host frog lineages in a mosaic contact zone

Parasites could differentially impact intraspecific host lineages due to genetic, phenotypic, ecological, or behavioural differences between the lineages, or the development of reproductive isolation between them. Batrachomyia (Diptera: Chloropidae) are flies that exclusively parasitize Australian frogs, and in the Wet Tropics rainforest of north‐east Australia larvae are largely restricted to the green‐eyed tree frog Litoria genimaculata (Anura: Hylidae). This frog species consists of two highly divergent genetic lineages that overlap in two nearby, but independent, contact zones. At one contact zone there has been extensive phenotypic divergence and speciation between the lineages whereas, at the other contact relatively lower levels of phenotypic divergence and reproductive isolation suggest that speciation has not occurred. In the present study we tested: (1) whether the deep phylogeographic divergence between northern and southern host populations is mirrored by congruent genetic structuring in the parasite populations and (2) whether the host lineages are differentially impacted by parasitism. We found that the two divergent frog lineages are parasitized by a single lineage of Batrachomyia, which exhibits strikingly little phylogeographic structuring. We found a significant difference in Batrachomyia prevalence between the host lineages at mixed lineage sites in both contact zones, with the magnitude and direction of this effect being consistent in both. The pattern did not differ between the two contacts even though recent phenotypic divergence and speciation has occurred between the lineages at one contact but not the other. Taken together, this suggests a fundamental difference in susceptibility between the genetically divergent host lineages. Using weight relative to body length as a measure of body condition, we found no differential impact of parasitism on the body condition of each host lineage, and no evidence that parasitism impacts the body condition of the host in general. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92 , 593–603.     

Changes in Wheat Leaf Extracellular Proteolytic Activity after Infection with Septoria tritici

The proteolytic activity of the leaf extracellular space of wheat cultivars Pigüé and Isla Verde was estimated after inoculation of either detached leaves or plants with the fungus Septoria tritici. Pigüé is resistant, whereas Isla Verde is susceptible to the disease caused by S. tritici. Viable conidiospores of the fungus caused similar increases in both hydrogen peroxide production and chitinase activity of the cultivars studied. In contrast, they caused a decrease in the extracellular serine proteinase activity of Isla Verde and a significant increase in that of Pigüé. Independently of the cultivar from which it was extracted, the extracellular serine proteinase inhibited the germination of Septoria tritici conidiospores. These results suggest that the proteolytic activity of the leaf extracellular space can participate in the defence of wheat plants against Septoria tritici. Its regulation may be controlled by specific defence components of each cultivar.     

Antibody to myelin constituents: A possible factor in induction of cell-mediated demyelination

Results from this laboratory have demonstrated that¹⁴C-labeled myelin opsonized with antibodies raised to purified CNS myelin in rabbit is phagocytized by cultured macrophages in larger amounts than untreated myelin or myelin opsonized with preimmune serum. The cultured macrophages produced high amounts of radioactive cholesterol ester and triglyceride from the antibody-treated myelin while much less was formed from preimmune serum-treated or untreated myelin. Antiserum to galactocerebroside also greatly enhanced the formation of radioactive cholesterol ester, while that to myelin basic protein as well as to other myelin constituents had little or no effect. Serum from Lewis rats with acute EAE 13–14 days after immunization with whole CNS myelin also stimulated radioactive cholesterol ester formation compared to serum from Freund's adjuvant-injected controls (FAC). Serum from EAE rats as a result of myelin basic protein injection was as active as that from rats with whole myelin injection. No galactocerebroside antibody could be demonstrated in the EAE sera, although a strong immunostaining to myelin basic protein and proteolipid protein was demonstrated. IgG prepared from EAE serum also showed stimulatory effects compared to IgG from FAC serum, but much of the activity was lost, and the possibility that other factors may be involved is discussed. These experiments provide evidence that myelin phagocytosis and digestion by macrophages is enhanced by the presence of antibody to myelin. In EAE this antibody may leak into CNS with the breakdown of the blood-brain barrier. A humoral involvement in demyelination in EAE is implicated, and these findings may be extended eventually to the demyelinative mechanism in multiple sclerosis where IgG is found in large amounts in the CNS.Special Issue Dedicated to Dr. Abel Lajtha.     

Fungispecificity of fluconazole against Candida albicans

Candida albicans is an opportunistic pathogen of human mucosal surfaces. Colonization of oral and vaginal mucosa by this yeast is antagonized by the resident normal bacterial population. However, antibacterial therapy can alter the normal flora to allow fungal cells to attach, grow and invade host tissues. We studied the antimicrobic activity of fluconazole against clinical isolates of oral and vaginal bacteria and Candida albicans in vitro and in vivo by scanning and transmission electron microscopy; we also compared the bactericidal activity of fluconazole with clotrimazole in vitro by microbiologie assay. Fluconazole lysed fungi but did not change the ultrastructure of bacteria. Clotrimazole, but not fluconazole, was bactericidal against lactobacillus and streptococcus, the principal species of the oral and vaginal cavities. We conclude that Candida albicans, but not oral and vaginal bacteria, is susceptible to fluconazole. These observations help explain the antimycotic specificity of fluconazole and its efficacy against candidiasis in humans.